Immunotherapy for hepatocellular carcinoma: A review of potential new drugs based on ongoing clinical studies as of 2019

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ContentslistsavailableatScienceDirect

Digestive

and

Liver

Disease

j o ur n a l ho me p a g e :w w w . e l s e v i e r . c o m / l o c a t e / d l d

Review

article

Immunotherapy

for

hepatocellular

carcinoma:

A

review

of

potential

new

drugs

based

on

ongoing

clinical

studies

as

of

2019

Francesco

Tovoli

a,∗,1

_,

_Andrea

_{Casadei-Gardini}

b,1

_,

_Francesca

_Benevento

a

_,

_Fabio

_Piscaglia

a a_Unit_of_Internal_Medicine,_Department_of_Medical_and_Surgical_Sciences,_University_of_Bologna,_Bologna,_Italy

b_Unit_of_Oncology,_Department_of_Oncology,_University_Hospital_of_Modena_and_Reggio_Emilia,_Modena,_Italy

a

r

t

i

c

l

e

i

n

f

o

Articlehistory: Received24December2018 Accepted1May2019 Availableonlinexxx Keywords:

Immunecheckpointinhibitors Nivolumab

Pembrolizumab Tremelimumab

a

b

s

t

r

a

c

t

Inthelatestyears,antineoplasticimmunotherapyrevolutionisedthetherapeuticlandscapeinoncology. Firstshowntobeeffectiveinmelanomaandnon-smallcelllungcarcinoma,immunecheckpointinhibitors arenowbeingtestedforthetreatmentofhepatocellularcarcinoma(HCC).Preliminaryresultshavebeen particularlypromising.Asaconsequence,anincreasingnumberofclinicaltrialsareunderway.Theroleof theimmunesystemincarcinogenesis(withparticularreferencetotumourescapeimmunemechanisms), aswellasthecurrentimmunotherapytrialsforHCCinitsdifferentclinicalscenarios,arethesubjectof thisreview.Inparticular,weaimtoprovidefreshupdatesaboutthesenoveltherapeuticagentswhich promisetoshapethefuturetherapeuticscenarioofHCC.

1. Introduction

Hepatocellular carcinoma (HCC) is among the most deadly cancersworldwide,despitesurveillanceprogramsandmany avail-abletreatments,includinglivertransplantation,surgicalresection, percutaneousand endovascularprocedures,aswellas pharma-cologicaltreatments[1].ThemajorityofHCCsoccurin patients whose liver suffered some degree of inflammation. The main risk factors for HCC include, in fact, HBV,HCV, obesity, exces-sive alcohol consumption and metabolic diseases, all of which contributetoaconditionofchronichepatitis,eventuallyleading tofibrosisandcirrhosis,heldaspre-neoplasticsituations. There-forethistumorappearsveryintriguingtotrytounderstandthe relationshipbetweentheimmunesystem,inflammationand can-cerdevelopment[2,3].It hasbeenhypothesised thatanaltered livermicroenvironmentcontributestoproduceHCCby reprogram-mingtheinflammatoryenvironment[4].Thus,anin-depthlookat liverimmunologyinHCCwouldimproveourunderstandingofthe immunologicalmechanismsthatoccurduring hepatocarcinogen-esisandcouldleadtonewandimprovedtreatmentstrategiesfor thisdeadlydisease.

∗ Correspondingauthorat:UnitofInternalMedicine,DepartmentofMedicaland SurgicalSciences,UniversityofBologna,HospitalS.OrsolaMalpighi,viaAlbertoni 15,40148Bologna,Italy.

E-mailaddress:francesco.tovoli2@unibo.it(F.Tovoli). 1 _Co-shared_ﬁrst_authorship.

This review concisely illustrates the mechanism of tumor immune escape and presents a complete standpoint of immunotherapy drugs under current clinical investigation for HCCasof2019.

Duringcarcinogenesis,thetransformationofnormalcellsinto malignant cells is associated with the expression of tumour-associated antigens (TAAs), that will be presented on the cell surfacebyagroupofproteinsknownasthemajor histocompat-ibilitycomplex(MHC)[5] (Fig.1A).Theseantigenswill alsobe retrievedandpresentedbyantigen-presentingcells(APCs).

TheAPCsmigratetolymphnodeswheretheydisplayTAAsto theT-cellreceptors(TCR)locatedonthesurfaceofimmatureT-cells (Fig.1B).However,thesimplebindingofTAAswithTCRsis insuf-ﬁcienttoactivateimmatureT-cells,butratheraco-stimulationis necessary.Inparticular,APCsandimmatureT-cellsco-stimulation requirethebindingofB7proteins(CD80/B7-1and CD86/B7-2), which are hosted on antigen-presenting cells, to CD28, which insteadispresentedbyimmatureT-cells.Thisbindingandthe con-sequentco-stimulationleadstotheactivationofsuchT-cells,which become CD8+T-cells (trigger phase) (Fig. 1C). The activated T-cellssubsequentlymigratefromthelymphnodestothelymphatic vessels andthen tothebloodstream untilreachingthetumour microenvironment. In thetumormicroenviroment CD8+T-cells recognisetheTAAspresentedbytheMHConthecancercellsand attackthem(effectorphase)(Fig.1D),eventuallyeliminatingtumor cells[5–7].

Thisprocessisobviouslyﬁnelymodulatedatalocalandgeneral level.Themostrelevantstepsforsuchﬁnemodulationdiscovered

https://doi.org/10.1016/j.dld.2019.05.006

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Fig.1. Interactionsbetweencancercellantigens(CCA)andtheimmunesystem. Aftertheirrelease,CCAreachtheantigenpresentingcells(A).Theidentiﬁcation ofCCAbytheantigenpresentingcellsleadstoaprimingoftheT-cellsandtheir eventualmigrationintothetumor(B).Thisphenomenonisnormallyfollowedbya T-cell-mediatedrecognition(C)andkilling(D)ofthecancercells.

sofararethoseinvolvingtheimmunecheckpointinhibitors, con-sistinginmoleculesboundtotheoutermembraneoftheimmune systemcells. Themostlargelystudiedimmune checkpointsare cytotoxicTlymphocyticprotein4(CTLA-4)andprogrammedcell deathprotein1(PD-1).

CTLA-4isessentialfortheactivationofCD4+T-cellsandthe triggeringphaseoftheimmuneresponse.ItsmainligandsareCD80 andCD86inactivatedT-cells.ThebindingofCTLA-4withthese ligandspreventtheirinteractionwithCD28,ﬁnallyresultingina decreaseinT-cellactivationbyantigenpresentation(Fig.2A).

CTLA-4is alsoconstitutively expressedbyregulatoryT-cells (Tregs)which areCD4+T-cellscharacterised by theexpression of CD25, CTLA-4, CD62L and FoxP3 molecules [8]. Once acti-vated,TregsinhibittheimmuneresponsethroughIL-2orproduce immunosuppressivefactorssuchasTGF-b,IL-10oradenosine[9]. TheyalsoneedCTLA-4tobeabletoexerttheirsuppressive activ-ity.Inadditiontoitsroleinmodulatingthetriggerphasethrough ablockoftheCD28,CD80andCD86interactions,CTLA-4also pro-motesimmunosuppressionwithinthetumour byinducingTreg activityanddifferentiation.

PD-L1 and PD-L2 are the PD-1 ligands (Fig. 2B). PD-L1 is expressedonimmunesystemcells(antigen-presentingcellsand

MDSCs),whereasPDL-2 isgenerallyexpressedinthe hemopoi-etic compartment. Severalcytokines, in particular, IFN-gamma, regulate PD-L1 [10]. After binding to its ligands, PD-1 inhibits CD8+T-cellactivationbyblockingTCRsignallingandalsoinhibits theactivationandproliferationofCD4+byincreasingIL-10 secre-tion.CancercellsexpressPD-L1andPD-L2,usingthismechanismto escapeimmunosurveillance.Infact,IFN-gammaproducedby TAA-speciﬁcT-cellsinasituationofchronicantigenexposure,induces PD-1expressioninT-reactivelymphocytesand upregulates PD-L1in APCsandtumour cells.ThePD-1–PD-L1graftthen blocks TCRsignallingandinhibitstheproliferationandsecretionof cyto-toxic T-cellmediatorsin a processknownas T-cellexhaustion. AltogetherthereforetheCTL4and PD-1/PD-L1pathwaysappear relevant in achieving (tumor) or blocking (therapy) the cancer immuneescape.

Accordingly,thepossibilitytotargetthecheckpointinhibitors pathway hasbeen a radical innovation in theﬁeld of the sys-temictreatmentsforHCCinrecent years[11].Theinhibitionof themostcriticalimmunecheckpointcanbereachedbyblocking CTLA-4,PD-1oritsligandPD-L1.Ipilimumabandtremelimumab are themostlonglytested CTLA-4 inhibitors.Nivolumab, pem-brolizumab,spartalizumab,camrelizumab,andtislelizumabhave shown a strong PD-1 inhibitory activity. PD-L1 blockers have beendevelopedmore recently,currentlyincludingdurvalumab, avelumabandatezolizumab.

2. Concludedtrials

Historically,tremelimumabwastheﬁrstcheckpointinhibitor testedexplicitlyinHCCpatients.Inaninvestigator-initiatedPhase IIopen-label,multicenter clinicaltrial,Sangro etalrecruited21 patientswithHCV-related HCC [12]. Most patients(57.1%) had anadvanced stagediseaseandwerenaïvetosorafenib (76.2%). Patientsweretreateduntiltumour progressionorunacceptable toxicity.Objectiveresponseanddiseasecontrolratewere17.6and 76.4%, respectively.Median time toprogression (TTP) was6.48 months(95%CI:3.95–9.14).Notoxicitiesrequiringsystemicsteroid treatmentwereregistered.

These favourable resultswere followed shortly afterby the announcement of a multicohort Phase 1b/2 trialof nivolumab alone or combined with ipilimumab in HCC (Checkmate-040, NCT01658878).Theresultsfromthedoseescalationandexpansion cohortsdisplayedanunprecedentedoverallresponserate(ORR)for systemictherapyinHCC[13].Acrossdoseescalationandexpansion

Fig.2.RolesofPD-1andCTLA-4checkpointsintheimmuneresponsetocancercells.WhiletheCTLA-4checkpointismainlyinvolvedthedendriticcells-mediatedpriming ofT-lymphocytes,thePD-1pathwayisprimarlyinvolvedintheinthedirectinteractionbetweenT-lymphocytesandtumorcells.

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phases(262patients),grade3/4treatment-relatedadverseevents occurredin20%.TheORRwas20%(95%CI:15–26)in214patients treatedin thedoseexpansionphasewithamedian durationof responseof9.9monthsandadiseasecontrolrateof64%(95%CI: 58–71).

Similar therapeutic efﬁcacy was observed in another open-labelnonrandomizedPhase2trialofpembrolizumabinpatients who progressed or were intolerant to sorafenib (Keynote-224) [14].Thismulticentrestudyenrolled104patientswhoreceived 200mgpembrolizumabintravenouslyeverythreeweeksuntil dis-easeprogressionorunacceptabletoxicity.TheORRwas17%,and thediseasecontrolratewas61%.Grade3treatment-relatedevents werereported in 24%of patients, and the mostcommonwere increasedaminotransferasesandfatigue.Asinglegrade4 (hyper-bilirubinemia)andagrade5treatment-relatedevent(ulcerative oesophagitis)occurred.Ofnote,immune-relatedhepatitisoccurred inthreepatientsbutwaseasilymanaged.Mostrecently,theresults ofnivolumabinthededicatedCohort5oftheCheckmate-040study wererevealed.In49treatedpatients(25sorafenib-naïveand24 sorafenibexperienced),theoverallresponseratewas10.2%with adiseasecontrolrateof55.1%, amedian overallsurvival of7.6 months,andasafetyproﬁlecomparablewiththatofChild-Pugh Apatients[15].

BasedontheresultsoftheCheckmate-040andKeynote-224 tri-als,theUnitedStatesFoodandDrugAdministration(FDA)granted onacceleratedapproval tonivolumab inSeptember2017and a priorityreview topembrolizumab for thesecond linesystemic treatmentofHCCinJuly2018.InJuly2018,theFDAalsogranteda breakthroughtherapydesignationforHCCtothecombination ate-zolizumabplusbevacizumabfollowingamulticenterPhase1btrial inwhichpatientswererandomisedin5differenttreatmentarms [16].Amongstthe23patientsassignedtothecombinationarm, 14(61%)hadanobjectiveresponsetotreatment.Otherregulatory agencies,suchastheEuropeanMedicineAgency(EMA),havebeen morecautioussofarandwillwaitformoreevidencebefore approv-ingthesemoleculesforHCC,eveninanondefinitivemodality.This callforcautionhasbeenshowntobejustifiedmostrecently,asthe Phase3Keynote-240trialdidnotconfirmtheresultoftheprevious Phase2trials,failingtodemonstratethebenefitofpembrolizumab overplacebointhesecondlinesetting[17].Inthefinalanalysis ofthestudy,therewasanimprovementinOSforpatientstreated withpembrolizumabcomparedtoplacebo,howevertheseresults didnotmeetstatisticalsignificanceperthepre-specified statisti-calplan(HR=0.78[95%CI,0.611–0.998];p=0.0238).Resultsfor PFSwerealsofavorableinthepembrolizumabarmcomparedwith placebobutdidnotreachstatisticalsignificance(HR=0.78[95%CI, 0.61–0.99];p=0.0209)[17].

3. Immune-relatedadverseeventsandoverallsafetyof immunecheckpointinhibitorsimmune-relatedadverse eventsandoverallsafetyofimmunecheckpointinhibitors

Inhibition of the physiological immune checkpoints can be associatedwithimmune-relatedadverseevents,bothorganand non-organspeciﬁc.Virtually,anytissueandorgancanbeinvolved [18,19].Intheseminalclinicaltrialsofnivolumab,theskin,gut, thyroid,adrenalglands,lungandliverwerethemostfrequent tar-getofimmune-relatedadverseevents[13].However,nivolumab wasoverallwelltoleratedandassociatedwithaverylowrateof grade≥3events, includingdiarrhea,pemphigoid-likeskin reac-tion,adrenal failure,and hepatitis [13].Ipilimumab aloneor in combinationwithnivolumab,wasinsteadassociatedwitha rel-ativelyhigher rateof aminotransferaseelevation (45%and 25% foraspartateandalanineaminotransferase,respectively)[12,20]. Theseimmune-relatedadverseeventsweregenerallyeasily

man-agedwithascheduledelayandcorticosteroidsinthemostsevere and/orunresponsivecases.Onlyaverylimitednumberoffatal out-comesduetoimmune-relatedpneumonitis[21]andmiocarditis [22]havebeendescribedsofarinthetreatmentofdifferent can-cers.Untilnow,asinglecaseofatreatment-relatedfataleventwas reportedinHCCtrialsofimmunecheckpointinhibitors(ulcerative oesophagitis)[14].

Despitethisreassuringsafetyprofile,theuseofimmune check-point inhibitors in the fragile setting of cirrhotic patients was initiallyaccompaniedwithajustifiabledoseofsafetyconcerns.In particular,theriskofimmune-mediatedhepatitisandthe possi-blesideeffectsderivingfromtheuseofcorticosteroidsincirrhotic patients were seen as critical elements. In the seminal study of tremelimumab in HCC by Sangro et al. [12], almost half of patientshada aminotransferaseincrease aftertreatment.These alterations were transient,never associated with liverfunction impairment,and didnotrequireprescriptionofcorticosteroids. IntheCheckmate-040study,anincreaseinaminotrasferase lev-els was found in 22–30% of the patients receiving nivolumab. A similar ratewas also described in the Keynote-224study of pembrolizumab [14]. These data have been also confirmed in thepreliminaryanalysisofotherPhases1–2trialsinvestigating differentagents, includingdurvalumab, camrelizumab,and ate-zolizumab[23–26].Theneedforcorticosteroidstotreatimmune relatedadverseeventshasbeenrelativelylow(maximum6%)so far[26].Overall,thesafetyprofileofimmunecheckpointinhibitors inHCCpatientswasconsistentwiththatreportedinprevious stud-iesformelanomaandlungcancer,suggestingthatthesepatients do notsufferanincreasedriskofliverimmune-relatedadverse events.Thesecomfortingdatafoundfurtherconfirmationinthe recentlypresenteddataofnivolumabinChild–PughBpatients.In thiscohortofparticularlyfrailpatients,treatmentrelatedhepatic adverseeventsweredescribedinonly4outof49patients,leading totreatmentdiscontinuationin2patients[15].

Inconclusion,immunecheckpointinhibitorsseemtobe gen-erally welltoleratedeven in patientswithHCC and underlying livercirrhosis.Todate,however,cautionisstillneededsincethese agents havebeentestedonlyintheveryrecent period,butare knowntopotentiallyproducealsodelayedtoxicities. More evi-dencederivingfromthelongtermfollowupofresponderpatients willhelpelucidatethisspeciﬁcpoint.

4. Ongoingtrials

Unsurprisingly, the interest toward immune checkpoint inhibitorsisontheriseinOncologyoverallandHCCisno excep-tion.Currently,morethan60studiesofthesemoleculeshavebeen registeredinClinicaltrials.gov.Thedesignofthesestudiesisvaried. Forinstance,checkpointinhibitorsarebeinginvestigatedassingle agentsorincombinationwithotherintheadvancedaswellasin theadjuvantandneoadjuvantsetting.Inthenextparagraphs,we willsummarisethesecurrentlyongoingstudies.

4.1. Advancedsetting—monotherapyorcombinationoftwo immunecheckpointinhibitors

Bytheendof2018,tothebestofourknowledge,ﬁvePhase3 randomisedclinicaltrials(RCTs)areexploringthissetting(Table1). In thesecondlinescenario,theKeynote-240 hasbeen recently announcedtohavefaileditsprimaryendpointofincreasedOSover placeboinaWesternsetting.TheKeynote-394trial,howeverisstill ongoingandtryingtoconﬁrmthesuperiorityofpembrolizumab overplaceboinEasternpopulations.

The competition is tougher in the ﬁrst line scenario, where nivolumab, tislelizumab and the combination

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tremeli-Table1

Ongoingclinicaltrialsexploringimmunecheckpointinhibitorsastreatmentforadvancedhepatocellularcarcinoma.

NCT Phase Studydrug(s) Line Primaryendpoint Estimatedendoftrial

NCT02576509 3 Nivolumabvssorafenib 1 OS Dec2019

NCT03298451 3 Tremelimumab(+durvalumab)vssorafenib 1 OS Mar2021

NCT03062358 3 Pembrolizumabvsplaceboa ₂ _OS _Apr₂₀₂₁

NCT02702401 3 Pembrolizumabvsplacebo 2 OS,PFS Feb2019

NCT03412773 3 Tislelizumabvssorafenib 1 OS May2022

NCT02519348 2 Tremelimumab(+durvalumab) 2 AEs,DLT Dec2019

NCT02658019 2 Pembrolizumab >2 DCR,AEs Apr2020

NCT02702414 2 Pembrolizumab 1–2 ORR May2020

NCT03163992 2 Pembrolizumab 2 ORR Dec2019

NCT03389126 2 Avelumab 2+ ORR Mar2020

NCT03419897 2 Tislelizumab 2+ ORR Sep2021

NCT01658878b _1B/2 _Nivolumab_vs_sorafenib ₁ _ORR _Jul₂₀₁₉

NCT01658878b _1B/2 _Nivolumab₊_ipilimumab ₂₊ _ORR _Jul₂₀₁₉

NCT02423343 1B/2 Nivolumab+galunisertib 2 MTD,AEs Dec2019

NCT02828124 1/2 Nivolumab Any AE Oct2020

NCT02940496 1/2 Pembrolizumab 2 Biomarker Dec2019

NCT:numberofclinicaltrial(Clinicaltrials.gov);OS:overallsurvival;PFS:progressionfreesurvival;AEs:adverseevents;DLT:doselimitingtoxicities;DCS:diseasecontrol rate;MTD:maximumtolerateddose.

a_Study_performed_in_Asian_population_only. b _Multi-cohort_study.

mumab/durvalumab are being tested versus sorafenib in their respectivePhase3RCTs.Theresultsofthesetrialsareexpected noearlier thanmid2019.In themeantime,preliminaryresults ofthetrials ofcamrelizumaband, durvalumabinmonotherapy orin combination withtremelimumab havebeen recently pre-sentedinabstractformatrelevantoncologymeetingsandseemto conﬁrmanobjectiveresponserateof15–20%withagoodsafety proﬁle[23–26]. Other interestingpreliminary datamight come fromsomeof thestill ongoing Phase 2 RCTs.In particular,the resultsoftheCohort3(nivolumabvssorafenib)andoftheCohort 4(nivolumab+ipilimumabvsplacebo)ofthealreadymentioned Checkmate-040studyareexpectedinlate2019.

4.2. Advancedsetting—combinationofimmunecheckpoint inhibitorswithotheragents

Thepossibilitytocombinethetherapeuticeffectsofdrugswith differentmechanism of action hasalways beenintriguing. The simultaneousblockadeofmanyneoplasticcrossroadsoffers,infact, ahigherprobabilityofobtainingadiseasecontrol.Inthespeciﬁc caseofHCC,thecombinationofanti-VEGFRagentsandimmune checkpointinhibitorscouldalsohavesynergisticeffectsgiventhe factthatmoleculartargetagentscouldcollectivelyblockthe sig-nallingfromvariousgrowthfactorsandaffectimmuneeffectors andthevasculature[27,28].Asaconsequence,mostclinical tri-alsofcombinedtherapyareexploringimmunotherapypairedwith oraltyrosineinhibitors(mainlysorafenib,lenvatinib,regorafenib, cabozantinib,vorolanib,andaxitinib)orintravenousanti-VEGFR monoclonal antibodies (bevacizumab, ramucirumab) (Table 2). Howeveramorepotentantitumoreffectisnotnecessarily asso-ciatedwithlongersurvivalinthespeciﬁcsettingofHCC,sincethis tumormostcommonlyarisesinabackgroundofadvancedliver disease,whoseworseningmightbeaslethalasthetumor progres-sion.ThisriskwasshownbythefailedsunitibvssorafenibPhase3 trial[29]wherethepotencyoftheantitumoraleffectwas under-minedbytheoccurrenceofseverecirrhosisrelatedadverseevents atthechoosendosage.

Inthefrontlinesetting,aPhase3RCTofatezolizumabplus beva-cizumabvssorafenibiscurrentlyongoingtoconﬁrmtheresultsof thePhase1btrialwhichledtheFDAtograntabreakthrough ther-apydesignationtothiscombination.Interestingdatacameformthe Phase1btrialofpembrolizumabpluslenvatinib.Amongstthe18 participantsofthestudy,almosthalf(46%)hadapartialresponsein

absenceofnewsafetyconcernssignals[30].Otherinteresting infor-mationmaycomefromtheCohort6oftheCheckmate-040study, inwhichthecombinationnivolumab(withorwithoutipilimumab) pluscabozantinibisbeingtested bothina mixedpopulationof sorafenib-naïveandpretreatedpatients.

Combinationstrategies of theimmune checkpointinhibitors arenot limitedtotheanti-VEGFR drugs. Inparticular,different trialsarealsoevaluatingcombinationswithtransforminggrowth factor-beta oral inhibitors (galunisertib), c-MET oral inhibitors (capmatinib),anti-phosphatidylserineantibodies(bavituxumab), andheatshockprotein90inhibitors(XL-888).Ofparticular inter-est,sometrials areexploringthemechanismsthatmayleadto thetumourresistance(andeventualprogressions)tothecurrently knowncheckpointinhibitors.The mainaimis toidentifyother modulatorsoftheimmunesystemwhichmayhelpin overcom-ingthisresistance.Forinstance,INCAGN01876isamodulatorof glucocorticoid-inducedtumournecrosisfactorreceptorwhichis beingtestedincombinationwithnivolumabplusipilimumaband pembrolizumab in two distinct Phase 1b/2 trials.Also, theC-C chemokinereceptor 4(CCR4) inhibitormogalizumabis claimed to enhance the antibody-dependenT-cell-mediated cytotoxicity and is currently being tested in combination with nivolumab. Similarly, EPACADOSTAT and INCAGN01949 are two drugs tar-getingindoleamine2,3-dioxygenaseandtheT-cellcostimulatory molecule CD134 which are being tested in combination with the current checkpoint inhibitors. Finally, the combination of immunotherapy and anticancer vaccines (Pexavec, T-VEC and p53MVA)isalsobeingexplored.

Whethersuchcombinationtherapieswillproduceahigherrate ofand/orlongerlastingantitumoraleffectandwilltranslateinto prolongedsurvivalforHCCpatientswillrequiresomeyearstobe demonstrated.

4.3. Adjuvantandneoadjuvantsetting

Toprevent,oratleastdelayrecurrenceafterachievinga com-pleteresponseoftheprimaryHCCwithresectionorlocoregional therapyhasalwaysbeenatargetofprimaryimportance.Infact patientsmaysufferspreadoftheprimarytumororoccurrenceof adenovotumordue totheunderlyingcirrhosis.Unfortunately, nodrugs have been foundable toachieve this goal in HCC so far.Inparticular,theSTORMtrialdidnotshowanyadvantagein patientstreatedwithsorafenibcomparedtoplacebointermsof

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Table2

Ongoingclinicaltrialsexploringimmunecheckpointinhibitorsincombinationwithotheragentsastreatmentforadvancedhepatocellularcarcinoma.

NCT Phase Studydrug(s) Line Primaryendpoint Estimatedendoftrial

NCT03434379 3 Atezolizumab+bevacizumabvssorafenib 1 OS,ORR JUN2022

NCT03439891 2 Nivolumab+sorafenib 1 MTD,ORR Dec2020

NCT03519997 2 Pembrolizumab+bavituximab 1 ORR Apr2021

NCT01658878a _1B/2 _Nivolumab_{(+ipilimumab)}₊_cabozantinib _Any _ORR _Jul₂₀₁₉

NCT02423343 1B/2 Nivolumab+galunisertib 2 MTD,AEs Dec2019

NCT03126110 1B/2 Nivolumab+ipilimumab+INCAGN01876 3 AE,ORR Mar2020

NCT02509507 1B/2 Pembrolizumab+T-VEC Any DLT,ORR Mar2023

NCT03211416 1B/2 Pembrolizumab+sorafenib 1 ORR Oct2019

NCT03418922 1B Nivolumab+lenvatinib 1 AEs,DLT Jun2020

NCT03511222 1B Pembrolizumab+vorolanib 2 RP2D Feb2022

NCT03289533 1B Avelumab+axitinib 1 AEs Aug2020

NCT02705105 1A/2 Nivolumab+mogamulizumab 3 MTD,DLT Oct2018

NCT02859324 1A/2 Nivolumab+avadomide 1–3 DLT,AEs,ORR Mar2020

NCT03241173 1A/2 Nivolumab+ipilimumab+INCAGN01949 2b _AEs,_ORR _Nov₂₀₂₁

NCT02178722 1A/2 Pembrolizumab+epacadostat 2–3 DLT,ORR Feb2020

NCT03277352 1A/2 Pembrolizumab+INCAGN01876 Any AEs,ORR Feb2020

NCT03071094 1–2A Nivolumab+pexavec 1 AEs,ORR Oct2019

NCT03475953 1–2 Avelumab+regorafenib 2+ RP2D,ORR Apr2021

NCT02795429 1–2 Spartalizumab(+capmatinib) 1 DLT,ORR Dec2019

NCT03382886 1 Nivolumab+bevacizumab 2–3 MTD, Mar2023

NCT03006926 1 Pembrolizumab+lenvatinib 1/2 AEs,DLT,ORR Dec2020

NCT03347292 1 Pembrolizumab+regorafenib 1 AEs,DLT Oct2020

NCT03095781 1 Pembrolizumab+XL888 2 RP2D Jun2023

NCT02432963 1 Pembrolizumab+p53MVA Any AEs Feb2019

NCT:numberofclinicaltrial(Clinicaltrials.gov);OS:overallsurvival;ORR:overallresponserate;MTD:maximumtolerateddose;AEs:adverseevents;DLT:doselimiting toxicities;RP2D:recommendeddoseforPhase2.

a_Multi-cohort_study.

b_Only_after_failure_of_previous_treatment_with_immune_checkpoint_inhibitors.

Table3

Ongoingclinicaltrialsexploringimmunecheckpointinhibitorsintheadjuvantandneoadjuvantsetting.

NCT Phase Studydrugs Setting Primaryendpoint Estimatedendoftrial

NCT03383458 3 Nivolumabvsplacebo ADJ RFS Jun2025

NCT03222076 2 Nivolumabvsnivolumab+ipilimumab NADJ AEs Sep2023

NCT03510871 2 Nivolumab+ipilimumab NADJ ORRa _Dec₂₀₁₂

NCT03337841 2 Pembrolizumab NADJ 1Y-RFS Oct2020

NCT03299946 1 Nivolumab+cabozantinib NADJ AE,FEASABILITY Mar2022

NCT:numberofclinicaltrial(Clinicaltrials.gov);ADJ:adjuavant;RFS:recurrencefreesurvival;NADJ:neoadjuvant;AEs:adverseevents;1Y-RFS:1-yearrecurrencefree survival.

a_Expressed_as_rate_of_patients_achieving_a_target_lesion_shrinkage_>10%.

recurrence-freesurvival[31].Moreover,thelowrateofobjective responseofsorafenibandothertyrosinekinasemadethesedrugs particularlyunsuitableintheneoadjuvantsetting.Immune check-pointinhibitorsmaytheoreticallyhavetheabilitytoenhancethe immuneresponseagainstresidualtumourcellsafterliver resec-tion.Furthermore,theirrelativelyhighrateofobjectiveresponse, particularlywhengivenincombination,couldalsobehelpfulin reducingtumourburdenwithinthecriteriaofsurgical resectabil-ityinsomepatientswithintermediateorevenadvanceddisease. Thevalidityoftheﬁrstpointhasbeenconﬁrmedbytheresultsofa Phase1trialoftremelimumabincombinationwithlocalablation procedures.Inthisstudy,32patientsweregiventremelimumab attwodifferentdoselevels,followedbysubtotalradiofrequency ablationorchemoablationatDay36.Nineteenpatientswere evalu-ableforresponse.Fiveofthemachievedacompleteradiological response.Nodoselimitingtoxicitieswerefound.Evenmore inter-estingly,tumorbiopsiesperformed6weeksaftertremelimumab revealedanaccumulationofintratumoralCD8+Tcells.TheAuthors thereforeconcludedthatthere-activatedimmunesystemcould potentiallyrecognizeandkillthecancerleftbehindbyasubtotal ablation[32].

Currently,nivolumab is beinginvestigatedversusplacebo in theadjuvantsetting followingcurativetreatments(resectionor localablation)inPhase3CHECKMATE-9DXtrial(Table3).Therole ofnivolumabaloneorincombinationwitheitheripilimumabor cabozantinibrespectivelyisalsounderinvestigationasa

presurgi-caltreatment.Similarly,atrialofpembrolizumabisalsoongoing intheneoadjuvantsetting.

4.4. Combinationofimmunecheckpointinhibitorswithlocal treatments

In rare circumstances, localised treatment of a metastatic tumourcanleadconcurrentlytoashrinkageofboththecancer lesiontarget(orwithinscope)oftherapyandofotheruntreated lesionslocalizedelsewhereinthebody.Describedfortheﬁrsttime afterlocalradiotherapytreatment,thisphenomenonhassincebeen named“abscopaleffect”.Ithasbeenpostulatedthattheliberation oftumour-associatedantigensafterthelocaldestructionleadto theprimingofimmunecells. Theoretically,immunecheckpoint inhibitorsmayenhancethisphenomenon.Asmentionedearlier, theCHECKMATE-9DXtrial willevaluatetheputativebeneﬁt of nivolumabnotonlyafterliverresectionbutalsoafterlocalablation. Phase2trialsarealsoevaluatingtremelimumabinasimilarsetting (Table4).Similarlytothelocalablationtreatments,even transar-terialtreatmentsmaypromotetheliberationoftumour-associated antigens.Combined treatmentsoftransarterial chemoemboliza-tionplusnivolumaborpembrolizumabareongoing.Transarterial radioembolization promotes radiation-induced tumour damage whichispartiallysimilartothatinducedbystereotacticbody radi-ationtherapy.Bothtechniquesarealsoexpectedtobeassociated withvariousimmunecheckpointinhibitorsindifferenttrials.

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Table4

Ongoingclinicaltrialsexploringimmunecheckpointinhibitorsincombinationwithlocaltherapies.

NCT Phase Studydrugsandprocedures Line Primaryendpoint Estimatedendoftrial

NCT02837029 1 Nivolumab+SIRT Any MTD Jul2020

NCT03033446 2 Nivolumab+SIRT Any ORR Dec2019

NCT03380130 2 Nivolumab+SIRT 1 AEs Oct2019

NCT03099564 1 Pembrolizumab+SIRT 1 PFS Jan2020

NCT03572582 2 Nivolumab+TACE 1 ORR Sep2022

NCT03397654 1B Pembrolizumab+TACE 1 AEs Dec2019

NCT03143270 1 Nivolumab+debTACE 1 AEs Apr2019

NCT03638141 2 Tremelimumab(+durvalumab)+debTACE 1 ORR Sep2020

NCT03203304 1 Nivolumab/ipilimumab+SBRT 1 AEs Aug2020

NCT03482102 2 Trememumab(+durvalumab)+SBRT 2 ORR Oct2025

NCT03316872 2 Pembrolizumab+SBRT 2 ORR Apr2022

NCT01853618 1 Tremelimumab+localablation 1 AEs Dec2019

NCT02821754 2 Tremelimumab+localablation 1 PFS Apr2021

NCT03630640 2 Nivolumab+electroporation 1 RFS Sep2020

NCT:numberofclinicaltrial(Clinicaltrials.gov);SIRT:selectiveintraarterialradiationtreatment;MTD:maximumtolerateddose;ORR:overallresponserate;AEs:adverse events;PFS:progressionfreesurvival;TACE:transarterialchemoembolization;debTACE:drugelutingbeadstransarterialchemoembolization;SBRT:stereotacticbody radiationtherapy;RFS:recurrencefreesurvival.

5. Conclusion

In conclusionimmunotherapy for HCCappears tobe a very intensefieldofinvestigation,raisingthehopethatnewvery effec-tivetreatmentopportunitieswillbecomesoonavailableleadingto newstrategiesinthemanagementofpatientswithHCC.Itis cur-rentlydifficulttomakepredictionsabouttheprecisescenarioof immunotherapyforHCC.Thetrialsunderwayarenumerousand theirfieldofapplicationrangefromtheneoadjuvantsettingtothe secondlinesystemictreatment,passingthroughtheadjuvantand frontlinesettings.Thecurrentscenarioisthereforeverydifferent fromthose historicallyfoundinOncology,whereanewdrugis initiallytestedinthesecondline,theninthefrontlinesettingif successful,andonlylaterintheadjuvantandneoadjuvantsetting. Itisthereforedifficult,ifnotimpossible,tomaketodaypredictions onpossibletherapeuticalgorithmsconcerningsequentialor simul-taneoustreatmentswithtyrosinekinaseandimmunecheckpoint inhibitors.Inadditiontotheresultsoftheindividualongoingtrials, otherfactorswillprobablybeinvolvedinthesealgorithms.Firstly, theimmunecheckpointinhibitorsarehigh-costdrugsanddifferent healthsystemscouldimplementdifferentalgorithmstakinginto accountsomeeconomicfactors.Secondly,thesafetyofthesedrugs iscurrentlyregardedasacceptableforpatientswithanHCCwhich isinitsadvancedstageorrefractorytoregionalsitetreatments. Thesepatientshaveinfactlimitedtherapeuticperspectivesanda poorprognosisinabsenceofanytherapy.Theadjuvantsetting,in whichpatientsreceivethesamedrugsbutwithabsentorminimal residualdisease,requiresgreatercautionandamorecareful assess-mentoftheriskoffataladverseeffects.Tothisextent,theresults of the numerous ongoing trials will help to betterunderstand thelong-termtoxicityprofileandthereforetoassesswhetherthe risk/benefitratioisacceptableevenintheadjuvant/neoadjuvant setting.Last,butnotleast,theresearchofbiomarkerpredictiveof responseismandatorytobetteridentifywhichpatientswillbetter respondtoimmunecheckpointinhibitorsandforwhichpatients thetreatmentwouldinsteadbefutile.Atthemoment,theonlysafe midtermpredictionisthatimmunotherapywillremainoneofthe hottesttopicsaboutHCCtreatmentinmanyofitsstages.

Conﬂictofinterests

FrancescoTovoli:consultantforBayer;

AndreaCasadeiGardini:consultantforBayer,advisoryboardfor Eisai;

FabioPiscaglia:speakerforBayer, Bracco, Eisai,GE,LaForce, AstraZeneca;advisoryboard forTizianaLifeSciences;research contractfromEsaote;

FrancescaBeneventohasnoconﬂictstodeclare.

Acknowledgement

None.

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